Half-Bloods at Half-Noon
by KiwiBird13
Summary: When Percy and Annabeth's train breaks down in the small town of Frog Creek, Pennsylvania, trouble is sure to follow. They soon discover a magical tree house with two curious little kids with a big secret. Find out what happens when worlds collide. Rated T cause I'm paranoid. I'm not trying to ruin an awesome little kids series. On hold.
1. Chapter 1

**So, I recently looked in the attic at my house and found all my old Magic Tree House books. These books are literally what got me into reading. I'm serious. I remember in, like, kindergarten being so proud because I could read chapter books. Then I decided to do a crossover with the Percy Jackson books, because there was the book,** ** _Hour of the Olympics_** **that had to do with Ancient Greece.**

 **Disclaimer: I do not own the Magic Tree House series or the Percy Jackson books.**

One sunny summer day, Percy and Annabeth were riding the train from Pittsburg to New York, when it broke down in the middle of nowhere. Well, not quite in the middle of nowhere. They were about a mile from the small town of Frog Creek, or so the driver had told them. They, along with the rest of the train's passengers, walked the mile to the town where they had been told to wait for another train that would come in about two hours. At least it was a nice day.

Meanwhile, two kids named Jack and Annie were planning their next trip to their magic tree house, a secret they had kept for a few months. Their most recent adventure with it? Ancient Greece. It had been 3 days since they got back, with no message from Morgan.

Percy didn't mind the walk to the nearest town, because he was with Annabeth. It had been 10 months or so since the Giant War had ended. They were walking though a wheat field. On days like these, Percy could almost forget Tartarus, about all they had been through and all that was yet to come. He thought about their trip to Pittsburgh. They had been visiting Grover, who was posing at a school looking out for demigods. They had stayed for one night, and now were headed back to camp.

Soon they reached the town. Frog Creek was a nice place, a small town that was cutesy and touristy almost. He and Annabeth found a nice place for lunch, a small café near the town center, then went for a walk in the Frog Creek woods to pass the time.

They came across an oak tree, one of the tallest around it seemed, with a little tree house perched between two branches at the top.

"Want to climb it?" Percy asked, half-jokingly.

"Sure. Why not?" Annabeth said.

She went up first.

"Whoever owns this tree house must have just been here, 'cause there are a ton of books that don't seem to be damaged by the weather. Kinda strange," Annabeth called down.

Percy climbed the rope ladder. The house was filled with research books, the kind elementary school kids used in school for projects. On the floor, a giant letter M was painted.

Annabeth picked up a book about Ancient Greece. It had been left open on the floor.

"Someone likes Ancient Greece, it would seem," she commented.

"And Rome," Percy added, picking up another book.

"And China," Annabeth continued, finding yet another.

She held up the Ancient Greece book. Outside, they could hear some kids. They seemed to be climbing the rope ladder.

"We'll explain when they get up here," Annabeth said. She looked at the book again. "Don't you ever wish we could go there, back in time?" she said, pointing to a picture.

The tree house started spinning. It spun faster and faster until everything was still.

Absolutely still.


	2. Chapter 2

**Hey guys. Sorry I haven't updated in a while. This chapter took me _forever_. I'll try to hurry up on the next one.**

Jack had been walking to the tree house with his little sister Annie when they heard voices coming from their tree house. No one had ever discovered it before. Jack had never really thought about what would happen if someone did. It had never been a problem.

"Who do you think that is?" he asked Annie.

"I don't know. Let's find out!" his little sister answered, energetic as always. She was seven and Jack was eight and a half. His sister enjoyed imagining things. Jack liked real things.

As they climbed the rope ladder, they heard a girl's voice say, "We'll explain when they get up here. Don't you ever wish we could go there, back in the past?"

Jack and Annie exchanged a look. Uh oh.

They quickly climbed into the tree house as it began to spin. When it stopped, they looked around. There were two other people in the tree house, teenagers, a boy and a girl. Their clothes . . . Jack looked down and saw that he, along with everyone else in the tree house, was wearing the same clothes as he had when they had gone to Ancient Greece and Rome. Oh no. The older boy was wearing a tunic, like Jack's, Annie was wearing a short dress, and the older girl was wearing a longer dress, all in a classic Greek style.

"Who are you?" the new girl asked.

"I'm Jack, and this is my little sister, Annie. I'm eight and a half and she's seven. Who are you?" Jack responded.

The teenagers looked at each other. "I'm Annabeth. This is Percy. Is this your tree house?"

"Um . . . this is a—a friends." Jack suddenly noticed something on the boy—Percy's—arm. "What's that? On your arm?"

Percy looked surprised, along with the girl, Annabeth. "You can see it?" he asked.

"Um, why wouldn't I be able to?" Jack asked. Why would this guy think he couldn't? "Can I take a look?"

"Sure . . ."

Jack examined it. "What is it?"

"A . . . tattoo, of sorts."

"This isn't a tattoo. It looks . . . is this a brand?" Jack had seen a brand before, on a cow once. "SPQR . . . that's an Ancient Roman phrase, isn't it? And the trident . . . that's the mark of Neptune, god of the sea."

Percy and Annabeth glanced at each other. "How'd you know that?" they asked in unison.

"I love anything to do with Ancient Rome. Where'd you get this?"

"A—an organization I was part of."

"Pretty strict organization."

"You could say that."

"Wait, wait, wait. What's going on? Why're we wasting time here when we can get back right now? We just need to find the Pennsylvania book . . ." Annie piped in. She searched the tree house. "Where is it?"

Jack searched as well. "I don't see it. Have you guys seen it?"

"Wait. Where are we? What's up with these books? Seriously, what's going on?" Annabeth asked.

Jack took a deep breath. This was going to be hard. "Okay, so this tree house is magic, it belongs to a magician friend of ours, Morgan Le Fay. Whenever we wish that we could go somewhere, by pointing to a picture in a book and saying 'I wish we could go there,' the tree house goes there. Please, we're telling the truth. In order to get home, we find the Pennsylvania book and wish on the Frog Creek page. While were travelling, no time at all passes at home."

"We've been on all sorts of adventures. We were just in Ancient Greece a few days ago. We've also been to Pompeii, the moon, the Amazon rainforest, Japan, China, Ireland—all over the place. The last place we went is, well, here. We go on missions for Morgan. Now we're Master Librarians," Annie said, holding up her card. Jack took his out, too.

The other two people nodded slowly. They look at each other, and then Annabeth said, "I've believed stranger things. Your story checks out, so yeah, I'll believe you."

"I trust Annabeth with whatever she says. I believe you," Percy said.

"Ooh, are you two _dating_?" Annie asked, teasingly.

 _Facepalm_. Annie! Why did she have to go off saying things like that. Percy and Annabeth were both blushing.

"Yeah . . ." Percy said.

"Are you gonna get _married_?" Annie asked.

"Annie!" Jack said.

"I don't know . . . Annabeth would probably judo-flip me if I asked right now . . . we're only 18 . . ." Percy stammered.

Annabeth smirked.

Annie burst out laughing. Jack had to smile. These two were pretty awesome. They were 18, which amazed Jack. They didn't act like adults, all mature. They were more like kids, laid back. Jack had never met anyone who was 18 before.

"How'd you guys meet? Do you go to school together or something?" Jack asked.

"We met at summer camp when we were twelve," Annabeth replied, "in New York."

"Cool," said Jack.

"Guys! Solve the problem now, bond later? We need to get out of here!" Annie burst out.

"Right. Right, we need a plan," Annabeth started. "You've been here before? How'd you get out?"

"We met a guy . . . Plato. He helped us. Let's hope we can find him again," Jack said.

" _Plato?_ _The_ Plato? The philosopher?" Annabeth asked in amazement.

"Yup. That's the one."

"Wow. What city are we in?"

"Um." Jack looked in the research book. "You pointed to this picture?" he asked, pointing. Annabeth nodded. "Then we're back in Olympia."

"Great. Now what?"

"We figure it out as we go along. Who's in?"


	3. Chapter 3

Annabeth's day had been going well enough. She had had a nice morning and lunch with Percy, and the weather was absolutely beautiful. Then they found the tree house, and everything went downhill.

Now she was walking through the downtown of an Ancient Greek city wearing an outfit almost identical to the one she had worn on Ithaca (an experience she would like to forget). There were two little kids with her, along with Percy, and she felt oddly responsible for them, and one of them wouldn't shut up.

"What's New York like? Do you guys know how to drive? Have you ever been out of the country? Why were you in Frog Creek? Do you two _love_ each other?" the little girl, Annie, asked.

Annie reminded Annabeth a little of herself, and not just because she was sometimes called Annie. Annabeth had been seven, Annie's age, when she ran away from home. Annie had had a much better childhood, though. She was curious, spoke her mind, and thought she could fix all the wrong in the world, like Annabeth had.

"Where's Plato?" Annabeth asked Jack as he led them through the city.

"He should be somewhere around here . . ." the boy replied, distractedly.

They were attracting attention now. People were starting to point.

Jack led them around a corner and, spotting someone, said "Here he is!"

"Plato, we're back!" Annie called, stopping her relentless questioning.

An older man turned and looked at the foursome. "Jack, Annie, welcome back to Olympia! Did you get out of trouble from your last time here?" He looked at Percy and Annabeth. "Who are these new people?"

"This is Annabeth and this is Percy," Annie replied.

"Hi," Percy said.

Annabeth was at a loss for words. "You—you're Plato!" she stammered. She had admired this guy her entire life.

"Why, yes I am," the older man said, incredulously. "Where do you come from?"

"We—we live in Athens. Jack and Annie here are our . . . cousins. We're on a family vacation," Annabeth replied, coming up with a story.

"Athens, huh? Athena's city?" Plato said.

"Yeah. Yeah, we've got connections with the goddess," Percy jumped in.

"I've never met a woman, besides Annie here, who speaks her mind so freely. It's nice to see," Plato mused.

"Oh, well, we come from a . . . a higher up family, which gives women more—uh—freedom." Annabeth silently cursed herself for coming up with such an elaborate story. How was she ever going to get out of this?

"Hmm," Plato said, unconvinced.

"Could you help us with a bit of a dilemma we're having? With the Master Librarian thing?" Jack asked.

"Of course, of course. Come with me."

Percy looked at Annabeth, like, _Are we really doing this?_ She nodded.

"Jack and Annie, talk with my friend over here. She'll be able to help. Percy and Annabeth, come with me. We seem to have much to talk about," Plato announced as they arrived at a large, prominent house. Plato led Annabeth and Percy down to a small office-type room, where he closed the door and sat down on a chair, and motioned for the two of them to do the same. They obliged.

"Who are you? Really? Gods in disguise? Demigods? Monsters?" Plato asked, leaning forward.

Annabeth glanced at Percy, questioning, like, _Should we tell him?_ He shook his head.

"No, just—just ordinary mortals. Nothing special like that. Anything else?" Annabeth opted to say.

"Are you sure?" Annabeth nodded. "Well then, we have no more to discuss. I am sorry for taking up your time. I believed—I believed you were someone else," the philosopher said.

"Thank you. May we go?" Annabeth asked, hoping to get out of there soon.

"Yes . . . yes, you may go."

Annabeth walked with Percy out of the study, and quickly pulled him into the closest private room, closing the door behind them.

"We need to talk. What's going on?" she asked him.

"I have no idea. But those kids . . . they can see through the Mist. I'm not sure what that means, but we need to get out of here, quick. No telling who could discover us if we stay too long," Percy whispered.

"Agreed. Now, how to get out of here?"


	4. Chapter 4

**Sorry again, I haven't been doing too well with posting new chapters. Cliffhangers, blah, blah, blah. I've been busy. Thank you to everyone who has review or liked or followed me or my fan fictions. You people are AWESOME! I do a little happy dance every time I see and email that someone had reviewed or followed or liked anything of mine. Now, without further ado(did I spell that right?), chapter four!**

Annie was bored. She had left Jack to talk with the poet they had met before after a few minutes, because their conversation was _so boring_. They kept going on and on about stories and stuff, and it seemed there would be no end.

Now she was exploring Plato's house, sneaking down corridors, checking out empty rooms, until she came across one with harsh whispers coming out of it. Annie crept closer, trying to catch what the people inside were saying.

"—do you think anyone knows?" she could hear. It was definitely a boy. She knew that voice . . . but from where?

"I don't know. Those kids . . . well let's just say the Hecate kids have taught me a bit about magic. Jack and Annie radiate that same kind of power. I'm not sure what it means." This voice was feminine, again familiar. "I hope they don't get caught up in what we've got going on. They're so innocent and sweet . . . I'd hate for anything to happen to them."

"The monsters here . . . not sure if they'd be stronger, or weaker, or the same as back home. I've got a feeling we're going to have a lot of company if we stay in one place too long."

"Definitely. Now let's go meet up with them—" Annie didn't stick around after that. She could hear people moving around in the room, getting up. She ran down the halls, thinking hard. Those people . . . Percy and Annabeth! That's who it was. Annie looked around for Jack

"Just—heard—someone—Percy and Annabeth—I think—talking—danger—magic—not sure what's going on—coming now," Annie panted, out of breath, when she reached her brother.

"Okay, okay, slow down. What exactly did you hear?" Jack asked her.

"They were talking about magic, and something called Hecate, and us radiating some sort of power, and monsters, and something about them being a danger to us. Not sure what any of it means, but they'll be here any minute. Don't think they'll be happy about me eavesdropping, will they?"

At that moment, the two teenagers walked into the room.

"Hey guys, find anything?" Percy asked as if nothing had happened. Annie guessed they hadn't noticed her listening in on them.

"A bit. Anonymous, that's what she wants us to call her, said that we might want to visit and oracle? Do you know what that is?" Jack reported.

Percy and Annabeth looked at each other.

"Yeah, we know what they are. Usually the oracles themselves aren't too bad . . . but those prophesies . . " Percy trailed off.

"Let's just say we know a thing or two about them and leave it at that," Annabeth said with a pointed look at Percy, as if he had said something wrong. Or let on too much . . .

Annie decided to break up the tension. "Are we going or what?"

"As much as I hate the idea, it's our best bet," Annabeth said.

"Sounds good to me," Jack added.

"Bye, Plato, thanks for helping us!" Annie called as they left the philosopher's home.

They set off through the streets of Olympia.


	5. Chapter 5

**Sorry I haven't uploaded for this in a while. This chapter's really long, so I hope that kinda makes up for it. Kinda. I don't have much else to say, so . . . here goes!**

Well, at least someone was having a good time. Annie seemed to enjoy this whole escapade more than anyone else. Jack, on the other hand, was not enjoying this at all. He felt like the two teens were keeping something from him and Annie, and he _hated_ being left in the dark. Trudging through the streets of Olympia with no real direction, just trying to find their way back to the tree house, was demoralizing. It seemed they would never get back.

"What, exactly, do you intend to do when we get to the tree house?" he asked Annabeth, slightly irritable.

"Look through that book of yours, see if there's anything about the Oracle at Delphi in there. That's the only good oracle I know of," she replied, ignoring his snappieness.

Finally, after what felt like hours, they found the tree house. Annabeth and Percy went first, then Jack and Annie. Annabeth immediately grabbed the Ancient Greece book, and began flipping through it. She stopped when she came to a picture of some ruins with a small caption.

"I wish we could go there!" she called out, before anyone could stop her.

"What are you doing?" Percy asked.

"Getting us to Delphi," Annabeth responded as the tree house began to spin. It spun faster and faster, until everything was still.

Absolutely still.

They were in a tree similar to the one in Olympia. The weather was similar, along with the landscape. A small cluster of buildings was nestled by a hill.

"Where are we?" asked Annie.

"Delphi," Annabeth and Percy said at the same time. They began to climb out of the tree house.

As they approached the buildings, Jack noticed a circular area, surrounded by columns. Nearby was a cave.

Annabeth and Percy immediately headed straight for the cave. Jack pulled Annie along behind them.

Inside the cave, a young woman sat on a three-legged stool. The ground beneath her was cracked, and from the cracks green wisps of smoke floated up. Jack heard coins clinking behind him, and he turned around. Annabeth was grabbing some large, golden coins from Percy's pack.

"An offering," she explained.

"Right," Jack replied.

Suddenly, the young woman on the stool began to speak.

"I am the Oracle of Delphi, speaker of the Phoebus Apollo. Approach, seeker, and ask." She opened he eyes. They were glowing green, the same color as the vaporous fumes coming from the floor.

" _Two kinds must travel, two men, two women, two mortals, two half-bloods,_

 _Before the time of the coming floods._

 _And when the moment may seem tragic,_

 _All will be well in the magician's magic._

"Thank you for your offering, have a nice day!" she then said, all of the mystical prophetess-ness gone.

Jack couldn't look away from her. He felt someone, probably Percy's hands on his shoulders pulling him outside.

" _We shouldn't have brought them_ ," he heard. " _It's probably not best for their sanity._ "

Suddenly, he was sprawled on the grass outside, staring at the blue, blue sky.

"What—what happened in there?" he asked.

"Shh, don't worry about that. Rest," Annabeth replied, calmingly. Jack didn't want to rest, though. He sat up.

"That—that oracle said something about—about—half-bloods? What does that mean?" Jack's mind was racing. "She also said mortals. ' _Two mortals, two half-bloods._ ' I know Annie and I are mortal. That makes you—half-bloods? What does that mean?"

Percy and Annabeth looked at each other.

"How about you just res—" Percy started.

"No! I want to know! You've been keeping me in the dark for the entire time about something! This is it! I don't care how much of a life-changing secret this is! We already told you ours! It's only fair!" Jack let all of his anger out. He got up, started pacing, thinking hard. "I've read something about half-bloods before! Harry Potter, wasn't it? Is that what you two are? _Wizards?_ "

"No—no we're not wizards . . ." Annabeth trailed off.

"We're—we're . . ." Percy seemed to choke on the last word.

"What?! What are you?" Jack demanded. He _needed_ to know. He just felt it.

" _Demigods_ ," Annabeth whispered, barely audible.

"Demigods? What's that supposed to mean?" Annie asked, finally speaking up.

"Half human . . ." Annabeth started.

"And half what?" Jack asked. Demi—that meant half. Okay, that left the second part. _God_. Half god. But that made no sense. "God?"

The teens nodded.

"I don't believe you. That—that's not possible, is it?" Jack was confused. Surely they were joking?

"Prove it," Annie said, quite simply.

Percy and Annabeth led them down the hill, to a river. Percy stood at the bank, with his back to Jack and Annie.

"Push me in," Percy said.

" _What?!_ Why?" Jack couldn't believe what he was hearing.

"Push me in," Percy repeated.

"Just do it," Annabeth said.

Annie ran at Percy's back, gathering as much speed as possible, and pushed him. Percy fell into the river. Unfortunately, so did Annie. She had too much momentum.

Percy's head came up almost immediately. For a scary moment, Annie's didn't. Then her now wet blond head popped up, laughing. She seemed to be sitting on a cushion of water, not using any effort to stay afloat. Jack glanced at Percy, and, with a shock, realized his head was completely dry. Percy walked out of the river, and not a drop of water on him. He gestured in the air, and Annie came flying ashore on a ten-foot wave.

"How?" was all Jack could ask.

"My dad. Poseidon. Lord of the water and blue food and all that good stuff. Any doubts now?"

"How'd you do that?" Annie grabbed Percy's hand and began examining it, as if for some sort of magical contraption.

"Honestly, I have no idea. Something about salt water and golden blood or whatever in my veins. It helps in life or death situations. And at parties," Annabeth smirked. "What? Anyway, you guys cannot tell _anyone_ about this. Anyone at all. No one. Ever. For the rest of your lives. You can obviously see through the Mist. That's how Jack was able to spot my Roman brand. That can be dangerous. Attracts monsters."

"Monsters?" Jack thought monsters were just make-believe. Sure, Annie sometimes played games with monsters, but he didn't think anyone _really_ believed in them. "And anyway, how'd you get that Roman mark? Poseidon is Greek, isn't he?"

"I don't like to talk about that. Hard eight months that was. For Annabeth, that is. I was asleep for most of it though—"

"Percy!" Annabeth acted like he had just said some sort of bad word. "Anyway, monsters, to answer your _earlier_ question" a pointed look at Percy "are none of your concern." Another pointed look.

"Who's your, like, god-parent thing?" Annie asked. Jack winced at her abruptness.

"Athena, goddess of wisdom and battle strategy."

"You have no idea how annoying she gets about that sometimes . . ." Percy whispered to Jack and Annie.

Annabeth glared at Percy. "Anyway. We need to get back to Olympia. I've got a feeling Plato will know a few things about this prophecy . . ."


End file.
